3D scanning helps uncover 350M-year-old tetrapod fossil in Scotland

Jan 11, 2017 | By Julia

Palaeontologists in Scotland have uncovered one of the first animals to crawl up out of the water and walk the shores of land. Meet “Tiny,” a small four-footed creature with a backbone, lungs, teeth, and five digits.

Hailing from Southern Scotland, Tiny is one of the first land-living vertebrates. As a Tetrapod – an evolutionary development that includes reptiles, amphibians, birds, and mammals – Tiny dates back about 350 million years, and her discovery marks a major breakthrough for palaeontologists.

Yet no one has actually seen Tiny, so to speak. Her fossil, which remains encased in unassuming black rock, bears no indication of the treasures inside. And without today’s technology, Tiny might remain undiscovered in that rock for ages to come, unbeknownst to scientists.

a reconstruction of one of the first Tetrapods

“We didn’t really know it was in the small piece of rock that we collected until it was CT scanned,” explains Dr. Nick Fraser, Keeper of Natural Sciences at the National Museum of Scotland in Edinburgh. “We were quite surprised to find Tiny hiding in the sediment - we still only know it from the 3D scan and the 3D print and so haven’t had the pleasure of seeing the actual fossil!”

While any fossil discovery is exciting, the revelation of Tiny is particularly significant, as she dates back to a time period that has, up until now, yielded very few fossils. Named after paleontologist Alfred Romer, Romer’s Gap references a period ranging from 360 to 345 million years ago (also known as the Tournaisian period), and a sizeable gap in our archaeological knowledge.

Romer’s Gap is precisely the time period when animals are thought to have begun living on land, yet a lack of fossils from the period obscures this crucial evolutionary development. It’s hard to say why the lack of fossils and other concrete evidence has occured. Mass extinction and low oxygen are two possible explanations.

Professor Jenny Clack, Emeritus Professor at the University of Cambridge, is chiefly to thank for the new finding. As one of the driving forces behind the research project TW:eed (Tetrapod World: early evolution and diversification), a group which spans the National Museum of Scotland, Universities of Leicester, Cambridge and Southampton, and the British Geological Survey, Professor Clack’s team has named five new species to date. Many more fossils have been found, but remain too fragmented to formally identify.

TW:eed’s work indicates there may be many more fossils yet to uncover from the elusive Tournaisian period, meaning Romer’s Gap may be less of a gap, and more of a blind-spot.

“It does appear that if there had been a ‘gap’ it was much smaller than previously thought, and might have affected some groups less severely than others,” Clack says. “There was an extinction event for many fish species, but no-one is really sure what caused it.”

So why the lack of fossils? “No one bothered to look at the right rocks previously,” says Clack. “Because they don’t yield commercially exploitable resources, these rocks did not have a history of accidental finds. So because no one had ever found anything, no one ever looked, and they were considered barren. It was a vicious circle.”

But with the recent influx of 3D scanning technology, researchers can now determine which rocks are the “right” ones much more easily. Gaining detailed CT scans of ancient unearthed rocks has opened up some revolutionary new discoveries, which in turn have helped scientists close the infamous historical gap.

a reconstruction of one of the first Tetrapods

Tiny is one of those discoveries. Small in size but gargantuan in palaeontological findings, Tiny’s existence was revealed through micro CT-scanning. This 3D scanning method allowed TW:eed researchers to digitally reconstruct Tiny in minute detail, without damaging her protective casing of rock. The fossil can remain entirely intact without sacrificing any of the data inside.

The importance of findings like Tiny can’t be overstated enough. By helping to map how our ancestor’s skeletons adapted to life on land, and when, fossils such as Tiny’s enhance our understanding of earth and its evolutionary diversity. They also provide a more accurate lineage of our own origins.

As Dr. Fraser explains, the first animals to walk the land with backbones constitute “a pivotal step in the evolution of life on land – without it there would have been no salamanders, no frogs, no crocodiles, no lizards, no dinosaurs, no birds, no mammals and therefore of course no humans.” In this sense, Tiny is actually one of our earliest ancestors – a discovery that may not be so tiny after all.